The invention pertains to a single facer apparatus for forming a single face web of corrugated paperboard. More particularly, the invention relates to a corrugating roll assembly comprising a large diameter corrugating roll (i.e. a bonding roll) and a small diameter corrugating roll in which alternate pairs of large and small corrugating rolls with different flute patterns may be rapidly changed.
In the manufacture of corrugated paperboard, a single facer apparatus is used to corrugate the medium web, to apply glue to the flute tips on one face of the corrugated medium web, and to bring a liner web into contact with the glued flute tips of the medium web with the application of sufficient heat and pressure to provide an initial bond. For many years, conventional single facers have typically included a pair of fluted corrugating rolls and a pressure roll, which are aligned so that the axes of all three rolls are generally coplanar. The medium web is fed into a corrugating nip formed by the interengaging corrugating rolls. While the corrugated medium web is still on one of the corrugating rolls, adhesive is applied to the flute tips by a glue roll. The liner web is immediately thereafter brought into contact with the adhesive-coated flute tips and the composite web then passes through the nip formed by the corrugating roll and the pressure roll.
In the past, the fluted corrugating rolls have typically been generally the same size as each other. More recently, a significantly improved single facer apparatus has been developed in which the corrugating rolls comprise a large diameter bonding roll and a substantially smaller diameter roll, with the ratio of diameters being 3:1 or greater. Such apparatus is disclosed in U.S. Pat. Nos. 5,628,865, 5,951,816, and 6,012,501, all which disclosures are incorporated herein by reference. In accordance with these disclosures, the single facer typically includes a backing arrangement for the small diameter corrugating roll. One preferred backing arrangement includes a series of axially adjacent pairs of backing idler rollers, each pair having a backing pressure belt entrained therearound. Each of the pressure belts is positioned to bear directly against the fluted surface of the small diameter corrugating roll on the side of the small corrugating roll opposite the corrugating nip. Each pair of associated idler rolls and pressure belts is mounted on a linear actuator, and can thus engage the small diameter corrugating roll with a selectively adjustable force. The application of force against the small diameter corrugating roll, in turn, applies force along the corrugating nip between the small diameter roll and the large diameter roll and along the full length of the nip.
In my co-pending application, filed on Oct. 9, 2001 and entitled xe2x80x9cSingle Facer Drive Apparatusxe2x80x9d, a single facer apparatus is disclosed in which the pressure belt arrangement for supporting the small diameter corrugating roll also provides rotatable drive to the small diameter roll from which driving rotation is transmitted through the nip to the large diameter corrugating roll.
There have been many attempts in the prior art to construct a single facer with interchangeable corrugating roll pairs so that a flute change can be made quickly and easily. Various types of apparatus have been designed for this purpose, including pairs of upper and lower corrugating rolls each mounted a rotatable spindle to change from one roll pair to another. Other constructions have provided means for simply lifting the rolls from operating position and replacing them with another pair.
With the introduction of the current state-of-the-art single facer using a large diameter bonding roll, roll replacement has become more difficult, even though the ability to rapidly change corrugating roll pairs remains just as important. It would, therefore, be most desirable and advantageous to provide for a quick corrugating roll pair change in a modern single facer of the type utilizing a large diameter bonding roll in cooperation with a much smaller corrugating roll.
In accordance with the present invention, three matching pairs of large diameter and small diameter corrugating rolls may be easily interchanged. The interchangeable large diameter corrugating rolls are carried on a rotatable turret and the small diameter corrugating rolls are supplied from a storage magazine positioned laterally offset from the turret and the single facer machine.
More specifically, a single facer apparatus for producing a single face web from a corrugated medium web and a liner comprising a rotatable turret carrying at least two, but preferably three, independently rotatable large diameter fluted bonding rolls on parallel rotational axes, a positioning device that is operable to rotate the turret to place a bonding roll into an operative position, a magazine carrying at least two, but preferably three, small diameter fluted corrugating rolls in a storage position offset laterally from the turret and the bonding rolls, a transfer device that is operable to move a corrugating roll axially from the magazine into an operating position adjacent the bonding roll in the operative position, and a corrugating roll support device to rotatably support the corrugating roll in operative engagement with the bonding roll. In the preferred embodiment, the transfer design is operable to move a corrugating roll axially to and from the operating position in the single facer and the storage position in the magazine.